Interpretive Summary: Gastrointestinal nematodes represent a major health challenge to small ruminants and effective alternatives to chemical dewormers are needed for organic production. Grazing sericea lespedeza is known to reduce fecal egg counts in goats and providing ‘AU Grazer’ sericea lespedeza has shown the same. However, it is not known how much of the diet comprised of sericea lespedeza will lead to an impact of gastrointestinal nematodes. Scientists at Fort Valley State University, Louisiana State University, USDA, ARS in Booneville, AR and Auburn University determined that 50-75 percent of ground sericea lespedeza hay in the diet has the potential to replace chemical anthelmintics. This information is important to producers, extension agents, veterinarians, organic certifiers, and scientists.

Technical Abstract:
Gastrointestinal nematode (GIN) parasitism is the greatest threat to economic sheep and goat production in the southern USA, and there is widespread prevalence of GIN resistance to broad-spectrum anthelmintics in this region. A natural alternative for controlling GIN in small ruminants is feeding hay of sericea lespedeza [SL, Lespedeza cuneata (Dum.-Cours. G. Don)], a perennial warm-season legume high in condensed tannins. To determine the level of SL needed to reduce GIN infection, a confinement study was completed with 32 Spanish/Boer/Kiko cross yearling bucks offered one of four diets with 75 percent hay and 25 percent concentrate (n equal to 8, two pens per treatment, 4 goats/pen). The hay portion of each diet consisted of a combination of ground SL (0, 25, 50, and 75 percent of the diet) and bermudagrass [BG, Cynodon dactylon (L.) Pers.; 75, 50, 25, and 0 percent of the diet]. The bucks were allowed to acquire a natural GIN infection on pasture prior to moving to the pens. After a 3-wk adjustment period in the pens, the goats were stratified by fecal egg count (FEC) and packed cell volume (PCV), randomly assigned to treatments and pens, and then fed the treatment diets for six weeks. During the experimental period, fecal and blood samples were collected from individual animals weekly to determine FEC and PCV, respectively. Adult worms were collected from abomasum and small intestines for counting and identification to species at slaughter. Goats fed SL hay at 25, 50, and 75 percent of the diet had 45.3, 66.3, and 74.5 percent lower FEC than control animals (75 percent BG hay) after 21 days. The 50 and 75 percent SL goats had 84.6 and 91.9 percent lower FEC than controls by day 42. There was also a dose response for PCV, with 75 percent SL-fed goats tending to have higher (P less than 0.10) PCV than the 25 percent SL and control animals, while the 50 percent SL goats were intermediate. The 75 percent SL goats had fewer (P equal to 0.035) abomasal worms than control animals, but the 25 percent and 50 percent SL worms were not different from controls. The optimum level of SL hay in the diet for reducing GIN infection of small ruminants appears to be 50-75 percent. Ground SL hay has potential as a natural supplement to or replacement for chemical anthelmintics.